The boulder berm of Punta Saguerra (Taranto, Italy): a morphological imprint of the Rossano Calabro tsunami of April 24, 1836?

Abstract

An extended berm of calcarenitic boulders is recognisable at Punta Saguerra, few kilometres south of Taranto (Apulia, Italy) while isolated boulders are sparse in other near localities. The berm is at 2-5 m above present sea level (a.p.s.l), on a rocky headland gently sloping toward the sea; it is separated from the coastline by a large terrace. A detailed study of its stratigraphy and its morphology has been performed in order to define its depositional mechanism; in particular, integrated DGPS and Laser Scanner surveys have provided precise details of each boulder: position, size and distance from the shoreline. The accumulation is constitute of boulders up to 30 tons, which locally are arranged in rows of embricated patterns. The surfaces of the biggest boulders are characterised by biogenic encrustations and by solution potholes that indicate their intertidal/adlittoral/spray zone provenience. Based on direct observations of each boulder (size, shape, weight and long axis azimuth), together with hydrodynamic equations it is possible to hypothesize the extreme event-geodynamic or meteorologicalwhich was responsible for this singular accumulation. AMS age determinations on Vermetid sp. sampled on boulder surfaces and chronicle suggest that the accumulation may be attributed to the tsunami generated by the strong earthquake that occurred on April 24, 1836, the epicentre of which has been localised near Rossano Calabro, along the Ionian coast of northern Calabria.

Sand Ridges on Rocky Coastal Platforms as Markers of Tsunami Impact: A Multi-Disciplinary Analysis along the Ionian Coast of Southern Apulia (Italy)

“…Further AMS age determinations on samples collected from the same coastal sand ridge are available from the literature; in fact, [27] report age data yielded by two samples of Columbella rustica (Samples BPS 1A and BPS 1B) at the S2 profile. Moreover, other AMS age determinations were performed on biogenic material collected at boulder accumulations in different places along the Ionian coast of southern Apulia, i.e., Baia d'Argento, Punta Prosciutto and Torre Castiglione [7,12,27] (Table 2). Taking into account a 2σ confidence interval, the calibrated ages obtained in this work span from 929-1168 AD (Sample ST1) to 1707-1950 AD (Sample ST6) ( Table 2).…”

“…In Southern Apulia, previous studies [7,8,12,13] associated the occurrence of large-size boulders accumulated at the coast with the effects of tsunami impacts during the last five centuries. Taking into account the Torre Squillace large-size boulder features, [33] calculated that the largest boulder detected in the area was dislodged from the cliff edge by an impacting tsunami wave with a minimum height of 4.94 m. The estimated maximum inland water penetration was of about 140 m and would be marked in the field by an erosive step occurring at the landward limit of the soil stripped belt.…”

“…Thus, it is not surprising that geomorphological research carried out during the last twenty years along the coasts of southern Apulia (Italy) has detected the effects of tsunami impacts which occurred during the past centuries [7][8][9][10][11][12]. They are mainly constituted by large-size boulders which can be found isolated, arranged in lines of imbricated elements or in large accumulations.…”

Análisis morfométrico de bloques de tsunami en la isla de Formentera, islas Baleares

“…En el Mediterráneo oriental se han realizado estudios de bloques de grandes dimensiones sobre las costas rocosas del Sur de Italia (Barbano et al, 2010;Mastronuzzi y Pignatelli, 2012;), en Grecia (Scheffers y Scheffers, 2007), en Egipto (Dalal y Torab, 2013), en Argelia (Maouche et al, 2009) (2014, 2015, 2016 a y b, 2017) los ampliaron a todo el archipiéla-go, asociándolos a diferentes fuentes tsunamigénicas que impactan en las islas Baleares (Roger y Hébert, 2008;Álvarez-Gómez et al, 2010Álvarez-Gómez et al, , 2011. El estudio de bloques de tsunami en Formentera han sido estudiados mediante análisis morfométricos en Punta Prima y Punta Gavina respectivamente (Roig-Munar et al, 2016a.…”

Numerical simulations to account for boulder movements on Lanyu Island, Taiwan: tsunami or storm?

“…Boulders are an indicator of high-energy events such as tsunamis or storms (e.g., Simkin and Fiske 1983;Harmelin-Vivien and Laboute 1986;Goff et al 2006;Goto et al 2009Goto et al , 2010aMastronuzzi and Pignatelli 2012). Boulders of Holocene coral limestone that had been transported by tsunamis were distributed on the beach and land areas of the south Ryukyu Islands (Kawana and Nakata 1994;Goto et al 2010b).…”